Dental or surgical instrument



Nov. 30, 1937. H. J. BRO WN ET AL DENTAL OR URGICAL INSTRUMENT Filed June 7, 1932 Patented Nov. 30, 1937 UNITED STATES PATENT OFFICE Harold J. Brown and George E. Farrell, Dorchester, Mass.

Application June 7, 1932, Serial No. 615,893

4 Claims.

The present invention relates to dental or surgical instruments.

One of the principal objects of the present invention is to provide an apparatus particularly suitable for dental surgery which is sufficiently powerful for such dimcult operations as removal of fractured roots, osseous chiseling, and the like, and yet sufliciently delicate to permit these operations being performed under the immediate control of the operator, and without excessive discomfort to the patient.

One of the most dimcult operations confronting the dental practitioner is the extraction of roots of inferior bicuspids. The accepted method of performing this operation is to cut a. window in the bone to permit sidewise removal of the root. The removal of the fractured portion of the root vertically is impossible with any instruments now in use, except by destruction of bone or process, because the usual elevator tools must be made of such bulk to resist the lateral pressures that they cannot be readily accommodated in the small space required for the operation. The extraction cannot be made a matter of delicacy and the patient is subjected to considerable operative shock.

According to the present invention, we provide an apparatus capable of delivering a series of light but positive and rapid reciprocations with a thin wedge-shaped instrument in the alveolar space between the root and the wall of the socket. The apparatus is specially constructed to operate with a sense of touch comparable to that with which the dentist is fa- 35 miliar in the use of the ordinary rotary engine. We have discovered that for an operation of this nature, a large amount of force is not necessary if the energy is applied at the proper place with sufflcient rapidity. It has been found possible to remove a fractured root in a comparatively small space of time and with little or no discomfort to the patient.

The invention is also applicable to the chiseling or shaving of osseous structure in order to gain access to malformed roots, impacted teeth, and the like. For such operation, as in the case of root removal, the apparatus is under the immediate, direct and complete control of the operator.

The present invention is also useful in the condensation of gold foil fillings. Such fillings ordinarily consume an inordinate amount of time and are attended with extreme discomfort because of the continual hammering under a series of sharp blows. Our invention produces a high.-

1y condensed filling in a short space of time under the influence of rapid but sufliciently light blows which produce no more than a minimum of discomfort.

Other features of the invention consist of certain novel features of construction, combinations and arrangement of parts hereinafter described and particularly defined in the claims.

In the accompanying drawing, Fig. 1 is a sectional elevation of the preferred form of the present invention; Fig.2is a section on line 22 of Fig. 1; Fig. 3 is a sectional elevation of the adjustable barrel; Figs. 4 and 5 are diagrams illustrating the use of the invention in the removal of fractured roots; Fig. 6 is a view partly in section of a form of elevator tool; and Fig. 7 is a detail view of a burnishing tool.

As shown in the drawing, the illustrated embodiment of the invention comprises a casing l0 preferably of light cast metal, having a headpiece i2 adapted to flt the nosepiece of the ordinary rotary dental engine. Journaled in the headpiece I2 is a shaft it which is received in the chuck of the nosepiece. The shaft carries at its inner end a small bevel gear i6 meshing with a bevel gear l8 which drives a cam 28 through spur gears 22. As shown in Fig. 1, this cam has three projecting portions 23. These are formed to give a difierent action depending on the direction of rotation of the shaft I4 for a purpose which will be described in detail later. The cam engages a reciprocating cam follower or plunger 24 which moves within a barrel 26 formed integrally with or suitably secured to the casing ill. The barrel 2B is arranged at an angle with respect to the axis of the shaft It in order that the instrument may be conveniently held by the practitioner in much the same manner as the usual rotary implements. The follower 24 extends through an opening in the end of the barrel 26 and is provided with a head 28 to limit the return movement. The follower is normally pressed into the position shown in Fig. 1 by a coil spring 30 which bears between the end wall of the barrel 26 and the collar 3| on the follower. The collar is held in place by a nut 32 threaded on the end of the follower.

Received on the barrel 26 is an adjustable tool carrier barrel 38 of the type shown in Fig. 3. This external barrel 38 is provided with internal threads 36 engaging with external threads of the barrel 26. The upper end of the external barrel rotates over an unthreaded portion of the barrel 26, this latter portion being provided with a plurality of spaced grooves Ell within which engage a plurality of indented detents 42.. The

' upper end of the external barrel 38 is made resilient by T-shaped slots 44. Therefore the external barrel 38 may be adjusted to any desired position merely by threading it to varying extents on the internal barrel. In the particular construction found most suitable for practical work, the internal barrel is provided with four ,of the grooves 40 arranged at 90, and the threads are of 5% inch pitch. Therefore, each quarter turn of the external barrel produces a longitudinal movement of 1/128 of an inch.

Received in the lower end of the external barrel 38 is a tool holder 43 which, as shown in Fig.'

2, is provided with four longitudinal grooves 45. A set of pins 46 threaded into the walls of the barrel engages in the grooves 45. The pins therefore serve as stops to determine the initial position of the tool holder 43 and also as means to position the member angularly with respect to the barrel. A tool 48 of any desired form is threaded into the tool holder43. A coil spring 50 bears between the end wall of the barrel and the end of the tool holder. The particular tool 48 illustrated in Fig. 1, is designed as a gold plugger, being used for condensation of gold foil fillings.

It will be noted that upon each revolution of the cam, the follower 24 is caused to undergo three reciprocations, all of uniform length. The follower engages the tool holder 43 and imparts thereto a stroke which is dependent upon the initial position of the external barrel 381. As shown in Fig. 1, there is considerable lost motion between the head 28 of the cam follower and the anvil 43, thereby resulting in a short stroke of the tool. The stroke of the tool may be increased by threading the external barrel 38 farther on the internal barrel. The angular position of the tool 48 is easily varied by pulling outwardly on the tool and then turning it through 90 to reset the slots 45 with relation to the pins 46.

As previously stated, the projections of the cam 20 are arranged to produce a different action depending on the direction of rotation of the shaft. Thus, when the cam is rotating in the counterclockwise direction, the plunger is actuated by the relatively smooth face A, whereas if the cam is rotated in a clockwise direction, the follower is actuated by the comparatively steep face B. The face A produces a smooth, light movement, and the face B is particularly designed to produce a more rapid and energetic blow near the end of the movement. All dental engines are designed for operation in either direction. Therefore the operator has a convenient control of the blow desired to be imparted.

In operation, the casing 10 rests in the fleshy part of the hand between the thumb and forefinger, while the thumb and the first two fingers lightly embrace the external barrel 38 near the lower end thereof. The instrument is therefore held in precisely the same manner as the usual drills and other implements with which the denaioosie set to give a short stroke to the tool generally not over of an inch. The engine is operated to drive the cam 20 in a clockwise direction to give a fairly sharp blow to the tool. Owing to the delicacy of the instrument, the practitioner is enabled to find the crevice between the root and the socket prior to starting the instrument. The tool is operated at 8 to 30, preferably about 20 strokes per second, thereby pressing the tool gradually through the alveola process. The tool 'may be made of extreme thinness, since it is required to undergo only longitudinal forces and since there is no necessity for lateral pressures as would be required in the ordinary hand elevators. If the series of light strokes does not succeed-in immediately loosening the root, the tool may be adjusted through to attack the process at another point.

For tenacious cases, a tool of the shape shown in Fig. 6 may be employed. This tool is of the same thin construction as that shown in Fig. 4, except that the rear face is made convex at the end. Immediately above the point portion 69 the front face is provided with a deep concave recess 60, the thickness of the portion 6| being slightly greater than the wall thickness adjacent tov the recess 60. In operation, the thin point portion works down through the crevice between the root and socket, then under the influence of the vibrating tool, the upper part of the root is free to rock slightly into the recess 60. In other words, the portion 6! acts as a fulcrum on which the root can rock, and the recess 60 provides a relief space to prevent binding of the partially loosened root on the tool. As the fulcrum progresses through the crevice toward the conical end of the root, the bond between the root and socket becomes progressively weaker until the root is entirely freed.

It is to be noted that the stroke imparted to the tool is a positive stroke occasioned by the striking of the plunger 28 against the anvil 43. A stroke of this type is to be distinguished from a stroke obtained by spring release or by a centrifugally actuated member, as ordinarily em= ployed in percussion instruments. The present invention provides for a lighter and yet more positive blow than can be obtained in an instrument wherein the force of the spring is utilized for actual delivery of the blow.

Fig. 5 illustrates a method of removal of 9, malformed root. As shown in this figure, the root has a bulb 62 at the base, this being shown in exaggerated form. Such a root can usually be distinguished by an X-ray photograph taken prior to the extraction. In order to remove a root of this nature, it is necessary to chisel away part of the bone structure indicated between the socket wall and the dotted line of Fig. 5. This is accomplished by the concave, straight-edged chisel tool 64. It has been found that a series of light blows imparted with sufiicient rapidity is successful in cutting away the bone to provide access to the root. It will be noted that this operation is far less radical than the usual methods of dental technique in that no more bone is removed than is necessary. For this operation, as in the case previously described, the operation can be carried out with a minimum of discomfort I of fillings. The tool 48 shown in Fig. 1 is adapted for goldfoil fillings. The tool has a serrated end portion 66 which serves to condense the layers of foil and form a substantially homogeneous struc- 5 ture.

effective to perform the operation with a mini mum of discomfort and in a small fraction of the time required with the usual hand implements. A similar tool may be used for amalgam fillings. The filling, after being condensed, may be burnished with a smooth-headed tool 68 of the type shown in Fig. 7.

Having thus described the invention, what is claimed is:

1. A dental or surgical instrument of the class described comprising a casing, a cam in the casing, a cam follower reciprocated by the cam, a tool holder reciprocated by the cam follower, the cam being constructed to present diiferent surfaces to the follower on the actuating movement of the latter, depending on the direction of rotation of the cam.

2. A dental or surgical instrument of the class described comprising a casing, a cam in the casing, a cam follower reciprocated by the cam, a tool holder reciprocated by the cam follower, the cam having a projection with a gradual rise in one direction and a steep rise in the other direction to permit change of the character of the 30 reciprocation of the tool holder depending on the direction of rotation of the cam.

The succession of light positive blows is.

3. In a dental instrument, the combination with a casing to be held in the operators hand and a tool holder reciprocable with respect to the casing, of an elevator tool carried by the holder to reciprocate on its longitudinal axis, the elevator tool having a shank and a thin walled operating portion of sumciently small dimensions to enter the crevice between a root and the alveolar socket, whereby the tool may be worked into the crevice to loosen the root without the application of lateral forces on the tool.

4. In a dental instrument, the combination with a casing to be held in the operator's hand and a tool holder reciprocable with respect to the casing, of an elevator tool carried by the holder to reciprocate on its longitudinal axis, the elevator tool having a shank and a thin walled operating portion, said latter portion being curved longitudinally from said shank portion and terminating in a point, the front face being formed with a deep elongated concave recess above the point, the point being thin and of sufliciently small dimensions to enter the crevice between a root and the alveolar socket, whereby the tool may be worked into the crevice to loosen the root without the application of lateral forces on the tool.

GEORGE E. FARRELL. HAROLD J. BROWN. 

